The present disclosure relates generally to the field of navigation display systems. More particularly, the present invention relates to a display system and method configured to optimize data sent over low bandwidth links to provide improved communications and display systems in aircrafts.
Displays are utilized in a wide variety of applications including but not limited to medical, military, avionic, entertainment and computing applications. In one exemplary application, displays are used in avionics to provide operators of vehicles, such as pilots or navigators, of information relating to weather and other aviation events. In some aircraft applications, instead of or in addition to analog dials and gauges, display screens provide the pilot with information about the situation of the aircraft, such as altitude, speed, and directional headings. Displays may also provide the pilot with navigation information, such as weather, no-fly zones, or other aviation events, as well as communication data between other aircraft, airports, or other ground-based systems.
Many aircraft have on-board instruments that gather information to be displayed in the cockpit, such as weather radar systems. Such weather radar systems typically include an antenna, a receiver transmitter, a processor, and a display. The system transmits radar pulses and receives radar return signals indicative of weather conditions. Conventional weather radar systems, such as the WXR 2100 MULTISCAN radar system manufactured by Rockwell Collins, Inc., have Doppler capabilities and are capable of detecting parameters such as weather range, weather reflectivity, weather velocity, and weather spectral width or velocity variation. Weather radar systems may also detect outside air temperature, winds at altitude, INS G loads (in-situ turbulence), barometric pressure, humidity, etc.
Weather radar signals are processed to provide graphical images to a radar display. The radar display is typically a color display providing graphical images in color to represent the severity of the weather. Some aircraft systems also include other hazard warning systems such as a turbulence detection system. The turbulence detection system can provide indications of the presence of turbulence or other hazards. Conventional weather display systems are configured to display weather data in two dimensions and often operate according to ARINC 453 and 708 standards. A horizontal plan view provides an overview of weather patterns that may affect an aircraft mapped onto a horizontal plane. Generally the horizontal plan view provides images of weather conditions in the vicinity of the aircraft, such as indications of precipitation rates. Red, yellow, and green colors are typically used to symbolize areas of respective precipitation rates, and black color symbolizes areas of very little or no precipitation. Each color is associated with radar reflectivity range which corresponds to a respective precipitation rate range. Red indicates the highest rates of precipitation while green represents the lowest (non-zero) rates of precipitation. Certain displays may also utilize a magenta color to indicate regions of turbulence.
While aircraft-based weather radar systems may typically provide the most timely and directly relevant weather information to the aircraft crew based on scan time of a few seconds, their performance may be limited in several ways. First, typical radar beam widths are 3 to 10 degrees. Additionally, the range of aircraft-based weather radar systems is typically limited to about 300 nautical miles, and typically most effective within about 80-100 nautical miles. Further, aircraft-based weather radar systems may be subject to ground clutter when the radar beam intersects with terrain, or to path attenuation due to intense precipitation or rainfall.
Information provided by aircraft weather radar systems may be used in conjunction with weather information from other aircraft or ground-based systems to, for example, improve range and accuracy and to reduce gaps in radar coverage. For example, the National Weather Service WSR-88D Next Generation Radar (NEXRAD) weather radar system is conventionally used for detection and warning of severe weather conditions in the United States. NEXRAD data is typically more complete than data from aircraft-based weather radar systems due to its use of volume scans of up to 14 different elevation angles with a one degree beam width. Similarly, the National Lightning Detection Network (NLDN) may typically be a reliable source of information for weather conditions exhibiting intense convection. Weather satellite systems, such as the Geostationary Operational Environmental Satellite system (GOES) and Polar Operational Environmental Satellite system (POES) are also primary sources of data used for weather analyses and forecasts.
Providing weather radar information from ground-based systems to aircraft-based systems may increase the range and accuracy of aircraft-based systems in certain conditions. A key issue with aircrafts collecting radar data from ground-based systems relates to image quality. For example, due to the limited bandwidth and throughput over systems such as ACARS, manufacturers often inhibit the amount of information provided to cockpits in an effort to simplify data transmission size and reduce computational complexity. In some instances, cockpit graphics manufacturers impose limitations on image quality, for example, by removing pertinent information from images, by displaying weather patterns larger than actual size to show more detail, or by over compressing images prior to transmission. Also, to reduce the size of transmitted images, color pallets used to depict weather patterns are often reduced from as many as forty-eight colors to as few as four colors. Coverage regions may also be predefined such that the user must select and receive data in regions with little or no relevance to the intended flight path. Similarly, coverage areas may also be limited such that some products are not available in certain regions.
Such image quality issues are further compounded by the types of graphics transmitted to aircraft from ground-based systems. Current systems typically employ graphic format types that require little computer processing capabilities, such as raster scan graphics. Most modern computer displays employ raster graphics in which each on-screen pixel directly corresponds to data stored in memory. The display is refreshed by scanning through pixels and determining an appropriate color for each individual pixel according to the stored data. Raster graphic images include images stored in common file types such as GIF, JPEG/JIFF, JPEG 2000, PNG, Exif, TIFF, RAW, and BMP, among others. One drawback of raster graphics is that image file size directly correlates to the number of pixels in an image and the image's color depth. Accordingly, some current image transmission and display systems reduce file sizes and image quality by limiting the number of colors used or compressing images before transmission. As opposed to raster graphics, vector image formats contain a geometric description which can be rendered smoothly at different desired display sizes. Instead of defining the color of each pixel on a display, vector image formats define images based on vectors that are led through control points. For example, a vector image may be defined as a series of instructions to draw images by defining the position and arrangement of control points that are connected by lines or shapes that, when combined together, define an image. Benefits of storing images in vector format can include smaller file sizes than raster image files, an ability to scale vector images to almost any size without a reduction in quality, and the ability to transmit additional information (e.g., metadata) in the image file.
Current aircraft-based systems typically provide weather displays with limited information that often require the aircraft crew to form mental images of actual weather or other aviation events rather than actually viewing an accurate image. There is an ongoing need for improved weather radar display systems and methods that display weather conditions and other aviation events using improved graphics. There is yet further need for improved weather radar display systems and methods that display weather conditions and other aviation events in selected regions relevant to the aircraft. There is further need for improved weather radar display systems and methods that provide flight crew with varying levels of display options.